Colored soluble cellulose



Patented Mar. 24, 1935 UNITE No Drawing Original application January 8,

1930, Serial No. 419,471, which is a continuation of pplication Serial No. 197,238, June 7, 1927. Divided and s pplication May 5, 1933, v-

.1 Claim. (01. 1134-79) This invention relates to colored soluble cellulose and particularly to pigmented soluble cellu lose as a new article of manufacture. The present application is a divisional application of my co-pending application Serial #419,471 filed January8, 1930, entiled Colored soluble and process for-making same."

Said application Serial #419,471 is a continuation of my application Serial #197,238 filed cellulose I June 7, 1927, now United States Patent #1,'I95,-

764. Colored soluble cellulose embodying my present invention may result from either the process of my United States Patent #1395364- or from the process of the said parent application hereto.

For the purpose of this invention, it may now be advisable to briefly define some of the terms which I will hereafter use in the manner that I wish them to be understood.

I define pigment as a solid, suitable for coloration, insoluble in water, as well as in the liquid which wets the compound, i. e. the fibrous solu-' ble' cellulose and pigment.

I define soluble cellulose as cellulose (CsH1oO5)$ treated chemically and thereby no longer corresponding to the carbohydrate (CsHioO5):t which' is cellulose. Soluble celluloses are celluloses in which hydroxyl-groups have been substituted'and thereby have been made soluble in the conventional sense.

I define fibrous as a quality of a substance capable of being spun and woven, therefore solid and undissolved.

I define pigment-pulp as a pigment sufii- 5 ciently damp or wet with a liquid (resembling mud) to permit of and accelerate its highest percentage of dispersion into fibrous soluble cellulose.

I define colored fibrous soluble cellulose as 40 the product resulting from the dispersion of pigment pulp into fibrous soluble cellulose.

I define an end product as a product utilizing or. containing colored fibrous soluble cellulose.

It is one object of my present invention to disclose a more efiicie'nt process for the handling of pigments, for example, the black pigments, such as carbon blackand lamp black. Carbon black, as now distributed, as powder in bags, is found to cover all objects adjacent the point of handling with black dust. This I will avoid. ,It is my further object to avoid the grinding of pigments dry as well as to avoid grinding with the conventional grinding media such as oils (castor oil), plasticizers (di-butyl-phth'alate) and resin solutions.

This grinding is often a time, money and labor consuming operation, for dry pigments often ofier great resistance to grinding, as may be recognized from the following: In general, the grinding of pigments into varnishes, oils, lac- 5 quers, etc... aims at the finest possible and most even distribution of pigments in the media surrounding them. To accomplishthis, it is necessary that, on the one hand the pigment must be very fine or of very small particle size, and that, m on the other hand, pigment and medium are most intimately mixed. At present, pigments. can be obtained from the manufacturer in a very fine state. The grinding of the pigment into the medium is, in fact, not accompanied by a fur- 15 ther disintegration of the pigment particle into smaller particles, for the medium acts as a lubrlcant, thereby diminishing friction of the grinding parts of the grinding machine. The grinding is in fact limited to a thorough wetting and pene- 2o trating of the pigment with the medium as well as squeezing and tearing apart of the balled and baked together primary particles, The thorough penetration of pigment by medium depends, in

a large measure, upon the surface tension at the 25 point of contact between pigment and medium. The smaller this factor of surface tension, the easier it is for the medium to completely wet and penetrate the pigment. On one side, therefore, one and 'the same medium acts difierently as re- 30 gards its wetting and penetrating qualities toward different pigments, and on the other side, one and the same pigment is wetted and penetrated in different degrees by difierent media. Apart from this tension of surfaces at the point of contact, wetting, depends also upon the te'ndency of the particle sizes to form agglomerates. Since dampness isconducive to this balling together, the pigments should be perfectly dry and free from moisture. Of course moisture would 40 also be detrimental to the finished product. Also during grinding there may be developed chemical and colloid-chemical problems together with the purely physical ones.

For perfect penetration of a pigment of a given 45 particle size, it is necessary to accomplish the following: I I

A. Wetting the particles with the medium.

B. Tearing apart of agglomerates thoroughly wetted though they may be. 5 Since viscous fluids such as oils, resin-solutions, cellulose-ester or cellulose-ether solutions are notoriously .bad wet 'ng media, pigments otler indeed great resistance to penetratlon'by them and therefore the long timerequired for grind 55 0n the other hand, soluble cellulose, when dissolved, possesses great vii-electric strength or is a goodinsulator which prevents these agglomerates from becoming discharged and the problem therefore becomes a grinding problem, namely,

a forceful disintegration and dispersion.

Now, soluble fibrous cellulose in its undissolved condition represents all the potential energies accumulated during its manufacture capable of being expressed in physical magnitude and therefore capable of measurement. These energies are available to cause a dispersion of the pigment pulp throughout the mass of the fibrous soluble cellulose. The situation is analogous to that of a steel watch spring which may be compared to the undissolved soluble fibrous cellulose. If thewound spring is dissolved in hydrochloric acid, the energy put into it by winding would be lost. The latent potential energies of soluble cellulose when still in fibrous form serve to defiocculate and disperse the pigment-agglomerates.

My process of producing colored soluble cellulose eliminates this time, energy and money consuming grinding. Lacquer, per se, is a poor wetting agent (medium) indeed, but some of its constituents are excellent wetting agents (such as alcohol) and my invention consists of selecting the good wetting agents (bearing in mind a particular type of end product) to do efiicient work, as such, the object being first creation of a pigment pulp. However, even after the pigments have been thoroughly wetted, the step of tearing apart the agglomerates'stilllremains to be done, for in order to accomplish the dispersion of the pigment evenly in the lacquer or other end products, having a soluble cellulose base, there must be no agglomerates. This tearing apart is accomplished by the fibers of the soluble cellulose when mixed together with the wetted pigment (pigment pulp). The fibers act to reduce the agglomerates into their separate individual particles. When this operation is finished, the production of colored soluble fibrous cellulose has been accomplished.

In order to make a final end product, such as colored or pigmented lacquer, all that needs to be done is to add a solvent, such as ethyl acetate, to the pigmented soluble fibrous cellulose, and when it is dissolved add the remaining constituents of commercial lacquer, such as resins, oils, diluents (gum damar, castor oil, toluene). So with any other final or end products such as artificial' leather, printers ink and the like.

The following examples will illustrate my invention. Dry or dried pigments such as: Ironoxides, siennas, ochres, umbers, titanium oxides, lithopone, zinc oxides, carbon black, lamp black, bone black, Prussian blue, ultramarine, zinc-chromate, lead-chromate, toluidine red, para-toner, lakes, such as alizarine-lakes and others, sulphur dyes, aniline black, chrome-oxides, graphite, in fact any dry or dried pigment, are first pulped in from 2 to 3 hours.

an eificient wetting medium to the specified fineness necessary to produce a pigment pulp, the pulping medium being preferably an organic liquid. While every particle in this pigment pulp is thoroughly wetted, it will develop, on standing, agglomerates physically resembling blood-clots. When this pigment pulp is mixed with fibrous soluble cellulose under agitation, these clots are separated by the fibers and colored fibrous soluble cellulose, damp or wet with the pulping me- .dium of the pigment pulp, and of the color of the pigment results.

The following examples will illustrate the process of making a black colored soluble fibrous cellulose:

Example I Placeinto a kneading machine or dough machine of the type of Werner & Pfieiderer, for instance, 250 parts of super spectra black, which is a carbon black of very high quality; then add, while the agitators are kept going, 600 parts of alcohol (-96%) and keep the agitators going until the black pigment is thoroughly wetted. This is easily recognized, for the black takes on a sheen. Now add, in small portions, 400 parts of alcohol-wet nitro-cellulose in fibrous form.

Agitators are keptin operation during this time until a stifi plastic dough is obtained. This takes A sample may be taken and dissolved in a small amount of ethyl-acetate. Of course, this dissolves only the nitro-cellulose, for the black is insoluble. Not more ethyl-acetate should be used than is just sufiicient to make a paste. This paste may be added to a small amount of clear lacquer and when this lacquer comes up to a required standard, the whole batch in the machine from which the dough sample was taken is finished colored nitro-cellulose, ready for use in any final or end product.

Example II Instead of wetting black pigment in a kneading machine, it may be done in a pebble-mill, which has the advantage of being enclosed and thus prevents the light and dusty black from permeating However, in, order Example III Into the kneading machine of Example I are placed 400 parts of alcohol wet fibrous nitro-cellulose. I mean by this commercial nitro-celluit is permitted to be transported in compliance with the specification of the I. C. C., i. e. containing about 30% alcohol of 90-96%. To this 400 lose as it may be purchased in the market and as parts of nitro-cellulose are 'now added, alternately, more parts of alcohol and then 60 parts of black pigment, then 150 parts of alcohol and again 60 parts of black pigment until the total in the '70 machine corresponds to Example I, i. e.:

400 parts alcohol-wet fibrous nitro-cellulose 600 parts alcohol 250 parts super spectra black It must be understood that while I have treated 75 2,084,861 3 of carbon black in the examples cited, I may use Iclaim:

any of the pigments mentioned and they are Apigmented productinwhich alcohol insoluwithin the scope of the appended claim. ble pigment particles are deflocculated and dis- Having thus described my invention, what I parsed by fibrous soluble cellulose in an alcoholic claim is new and desire to secure by Letters Patent medium.

5 of the United States is:

EMILE DE STU'BNER. 

